DESCRIPTION: The long-term goal of the research is to better understand the socio-biology of cognition. The proposed study will investigate relationships between social variables, circulating gonadal hormones, and cognition during three developmental stages: infancy, adolescence, and adulthood. Testing methodologies have been validated with each developmental group in previously published studies or in pilot studies. The experiments use between- and within-subject procedures. A between-subjects component is possible because gonadal hormones vary widely among individuals within genders as well as between genders during infancy and adolescence. A within-subjects component is possible because the same adolescent subjects will be studied for three consecutive years as they progress through puberty. Adult control subjects will have a minimum of within-gender hormonal variation and a maximum of between-gender hormonal variation. Infants will be tested on tasks that show male and female superiorities in infant monkeys and children. Adolescents and adults will be tested on tasks that are gender-specific in adults. Cognitive, hormonal, and social data have been collected on 164 preadolescents in the seventh grade. In the proposed research, 250 new subjects will be similarly studied for three consecutive years starting in the seventh grade. Over the course of 3 years, nearly all of these subjects should attain adult or near-adult hormonal status. In all groups, blood spots (finger prick) will be assayed by radioimmonoassay for testosterone and estradiol. In all groups, data will be collected relative to familial SES and education, and subject activities and interests. In the two older groups, data will be collected concerning the subjects grades, standardized tests, and individual gender traits, attributes and activities. Analysis of variance and regression analyses will determine the relative contribution of hormonal and social factors to cognition among members of each gender and between genders.